Anti Static Flooring for Public Safety Emergency Communications Applications: Which Resistance Range is Correct – Static Dissipative or Conductive?
Which ohms resistance rating is correct for grounded static control flooring used in end user operational* equipment, communication and data storage environments? This is a question that many have found difficult to answer.
Much of the confusion has been caused by the misapplication of ESD flooring standards as utilized in ESD protected areas (also known as EPAs) by the electronics manufacturing and explosives handling industries. Other industries, such as telecommunications and data centers, adher to their own principles of grounding and surge protection adapting for the unique criteria of a 24/7 mission critical environment.
This article seeks to clarify any misunderstandings industry professionals may have through the presentation of informational data and a list of corresponding resource and organizational links. (Please note: ESDA document ANSI/ESD S20.20-2007 is not mentioned and S20.20 is meant for program managers overseeing the design and implementation of static control processes in ESD protected areas within an exhaustive program of electronics manufacturing environments.) This article's main focus is on the concerns of non-factory, end user operational equipment, such as networked office spaces, data centers and emergency dispatch centers.
While conducting research for an article to be published by the September 2011 issues of The Construction Specifier, we examined FAA, telecommunications and computer industry grounding, lightning, electrical surge and safety standards. This study resulted in a confirmed knowledge that lays to rest outdated assumptions regarding the appropriate electrical specifications of floors – especially carpeting - installed in environments where static sensitive operational equipment is used. Many ESD flooring distributors have falsely assumed that conductive flooring measuring between 2.5 X 10 E4 and 1.0 X 10 E6 was acceptable for these end user environments. Their static prevention strategy was transferred from unrelated requirements involving the mandatory use of conductive flooring when handling explosive or flammable materials. This assumption and the applicability of explosives grade flooring for installation in end user environments – often publicly accessible places - is incorrect and leads to unnecessary risks. Conductive flooring fails to meet pertinent grounding standards for telecommunication equipment end user spaces.
Five distinct authorities/standards organizations agree that a recommended ohms resistance range for the flooring applications discussed here does exist. Separately, they each recommend an ohms range above 1.0 X 10 E6 and below 1.0 X 10 E9 for end user spaces like server rooms, 911 call centers and data centers.
Specifically we examined the standards and recommendations of the following organizations:
IBM Publications Center
- Link to IBM site recommendation and physical planning
- IBM's Recommended range of flooring 1.5 X 10 E5 – 1.0 X 10 E10 ohms
- A common document referenced by data center designers
- The Motorola guidelines have become the recognized standard in the industry and serve as the most complete and rigorous specification for the protection of communication system equipment installed at public safety and commercial wireless communication sites
- Link to Motorola R56 See pages 468-470
- Excerpt from Appendix C 3.3 - 68P81089E50-B (9/1/05 — UP Version):
"Carpeting or floor tiles within an equipment room or dispatch center, including raised flooring, should have a resistance to ground measurement of between 106 and 109 ohms when measured using the test method of ANSI/ESD STM7.1-2001 or later"
- Alliance for Telecommunications Industry Solutions
- Electrical Protection for Network Operator-Type Equipment Positions
- Link to ATIS-0600321-2010 Protection for Network Operator-Type Equipment Positions
- Available for purchase: Digital Edition available from www.engineers.ihs.com
- Excerpt from Page, Section 4.2 Flooring:
"Any carpeting or floor tiles should have a resistance to ground between 10 E6 and 10 E10 ohms when measured using the method of ESD-S7.1.”
- ATIS publishes standards for the information, entertainment and communications industries
FAA STD 019e
- Link to FAA STD 019e Lightning and Surge Protection, Grounding, Bonding and Shielding
- Excerpt from section 220.127.116.11.3.5 Static Dissipative ESD Floor Coverings
- Recommended range of flooring 1.0 X 10 E6 – 1.0 X 10 E9 ohms
- The 019e document supersedes a previous document (019d) where conductive flooring was considered acceptable.
Produced by UNINETT
- Working group on physical infrastructure
- (No UFS103) Author: Stein Nygaard: May 2010
- Link to: Requirements for the Design of ICT Rooms - Best Practice Document
- Recommended range: The resistance between any point in the floor covering and earth shall be from 1,0 X 10 E6 to 1,0 X 10 E7_, cf. NEK EN 50174-2009
Section 3 – Subsection 9 General Requirements
As you review these organization’s recommended parameters keep in mind 3 factors:
- All organizations cited in this article approved the use of materials measuring in the static dissipative range.
- When evaluating an ohms rating expressed in scientific notation, keep in mind that the difference between each ascending exponent is a multiplier of 10. For example 1.5 X 10 to the 4th = 15,000 ohms --- 1.5 X 10 to the 5th = 150,000 ohms
- A floor measuring between 2.5 X 10 E4 and 1.0 x 10 E6 is defined as a conductive floor.
- A floor measuring between 1.0 X 10 E6 and 1.0 X 10 E9 is defined as a static dissipative floor.
*Operational equipment is the same as energized equipment.
As part of our research, we contacted a member of the committee overseeing Motorola R56. The purpose of contact was to determine if Motorola planned to modify their electrical resistance range for acceptable static control carpet in the near future. The published range since 2005 has been 1.0 X 10 E6 to 1.0 X 10 E9 ohms. There is currently a new draft of R56 in the works. As with other grounding and electrical standards organizations like ATIS and FAA 019e, we were told that Motorola’s acceptable resistance range will remain in the static dissipative range from 1.0 X 10 E6 to 1.0 X 10 E9.
Below is an excerpt of the flooring section as it will appear in the new draft:
Motorola R56 Appendix C
PROTECTING AGAINST ELECTROSTATIC DISCHARGE (ESD) IN EQUIPMENT ROOMS AND DISPATCH CENTERS
Carpeting or floor tiles within an equipment room or dispatch center, including raised flooring, should have a resistance to ground measurement of between 106 and 109 ohms when measured using the test method of ANSI/ESD-S7.1-2005 or later. Existing flooring that does not meet this requirement should be treated with a topical solution such as an antistatic floor wax or spray solution. The effectiveness of antistatic solutions is temporary and varies with floor material and relative humidity. Flooring resistance should be monitored every two weeks minimum to verify conformance to the above requirements. See ATIS-0600321.2010, section 4.2 and ANSI/ESD-S7.1-2005 for more information.
When ESD protective flooring is used, the following should be observed:
- ESD protective flooring shall be installed per the manufacturer's recommendations.
- ESD protective flooring and floor coverings should be installed, grounded, and tested by trained installers.
- Personnel entering the equipment room or dispatch area should wear ESD dissipative footwear or dissipative foot straps. The footwear should provide dissipative resistance values of less than 3.5 ´ 107 ohms as measured according to the measuring requirements within ANSI/ESD STM97.1-2006 or later. The footwear should also provide dissipative resistance values of less than 1.0 ´ 109 ohms as measured according to the measuring requirements of ANSI/ESD STM97.1-2006 or later.
- When ESD protective flooring is not installed at a dispatch position or equipment room, an ESD protective floor mat should be installed at the work areas.
- The floor mat should provide dissipative resistance values between 106 and 109 ohms when measured using the test method of ANSI/ESD-S7.1-2005 or later.
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